Tests of disk type magnetic flux pump with the ability of high voltage output

Tsukiji, Hiroshi; Choi, Kyeongdal; Tsukiyama, M.; Nishiya, T.; Hoshino, Tsutomu; Mukai, Eiichi; Muta, Itsuya

doi:10.1109/77.614512

Cited by 10 publications

(3 citation statements)

References 5 publications

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“…Superconducting dynamos employing low-temperature superconductors (LTS) have been reported by various previous authors. 2,[18][19][20][21][22] These devices utilise materials with a low B c2 such that a "normal-conducting spot" is considered to form in the high field region beneath the rotor magnet. 1 However, a normal spot is not formed in our HTS dynamo, as B c2 (at 77 K) of the YBCO coated conductor used in this work is much greater 23 than the applied rotor field of $0.2 T. Instead, flux vortices will penetrate in the high field region beneath the rotor magnet and move through the HTS tape.…”

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confidence: 99%

Anomalous open-circuit voltage from a high-Tc superconducting dynamo

Bumby

Jiang

Storey

et al. 2016

Applied Physics Letters

101

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We report on the behavior of a high-T c superconducting (HTS) homopolar dynamo which outputs a DC open-circuit voltage when the stator is in the superconducting state, but behaves as a conventional AC alternator when the stator is in the normal state. We observe that this time-averaged DC voltage arises from a change in the shape of the AC voltage waveform that is obtained from a normal conducting stator. The measured DC voltage is proportional to frequency, and decreases with increasing flux gap between the rotor magnet and the HTS stator wire. We observe that the DC output voltage decreases to zero at large flux gaps, although small differences between the normal-conducting and superconducting waveforms are still observed, which we attribute to screening currents in the HTS stator wire. Importantly, the normalised pulse shape is found to be a function of the rotor position angle only. Based on these observations, we suggest that the origin of this unexpected DC effect can be explained by a model first proposed by Giaever, which considers the impact of time-varying circulating eddy currents within the HTS stator wire. Such circulating currents form a superconducting shunt path which "short-circuits" the high field region directly beneath the rotor magnet, at those points in the cycle when the rotor magnet partially overlaps the superconducting stator wire. This reduces the output voltage from the device during these periods of the rotor cycle, leading to partial rectification of the output voltage waveform and hence the emergence of a time-averaged DC voltage.

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confidence: 99%

Anomalous open-circuit voltage from a high-Tc superconducting dynamo

Bumby

Jiang

Storey

et al. 2016

Applied Physics Letters

101

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“…This exciting method has some problems: heat leak into the cryogenic part, occurrence of joule loss in the power leads, and etc. Therefore, it is preferable to design a superconducting power supply that can operate under cryogenic environment in order to transfer the energy to the superconducting load without unwanted loss [1], [2]. By using a superconducting power supply, conventional current leads for a superconducting magnet could be replaced with superconducting leads to charge the magnet.…”

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confidence: 99%

Design and Test of a Superconducting Power Supply With YBCO Coated Conductor Load

Yoon

Yang

Cho

et al. 2008

IEEE Trans. Appl. Supercond.

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This paper deals with the design and test of a high temperature superconducting (HTS) power supply with YBCO coated conductor (CC) pancake load, also presents its operational characteristics through experiments. HTS power supply consists of two heaters, an electromagnet, a solenoid, and a pancake load of about 0.73 mH. The solenoid and pancake load were fabricated by using YBCO CC. The timing sequential control of two heaters and an electromagnet is an important factor to generate pumping-current in the pancake load. The heat transfer analysis of heater triggering parts of the YBCO CC solenoid according to the heater input was carried out. Based upon the analysis, the 3 A electromagnet current and the 0.55 A dc heater current were optimally derived, and 4 s, 8 s and 16 s for the pumping period were selected in this experiment. A region of the superconducting tape with a buried heating coil can be switched by means of its temperature change. In order to measure the pumping-current with respect to the magnet flux changes, a hall sensor was installed at the center of the YBCO CC pancake load. In the experiment, the maximum pumping current reached about 20 A.

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“…Superconducting dynamos employing low-temperature superconductors (LTS) have been reported by various previous authors. 2, [18][19][20][21][22] These devices utilise materials with a low B c2 such that a "normal-conducting spot" is considered to form in the high field region beneath the rotor magnet. 1 However, a normal spot is not formed in our HTS dynamo, as B c2 (at 77 K) of the YBCO coated conductor used in this work is much greater 23 than the applied rotor field of $0.2 T. Instead, flux vortices will penetrate in the high field region beneath the rotor magnet and move through the HTS tape.…”

mentioning

confidence: 99%